03 March 2010; On the way to Recife, Brazil.

Slowly we start to understand how large Brazil is. On the 26th of February we passed the border between Uruguay and Brazil and ever since that time we have been sailing along its coast. Between Rio and Salvador we sailed at full speed and now we are sailing along with the sedate speed of 14 knots; set to arrive at Recife at sunrise. After that we still have several days of steaming to go, interspersed with ports and the Amazon of course, before we will finally come to another country. However those countries, Guyana, Suriname etc. are still laying along the coast and form a rim around Brazil. It is indeed a very very big country. Thus today we sailed along another part of the coast of Brazil. That coast was about 60 miles to the West of us as we are following a straight course line and the Brazilian coast is curved inwards here. Only in the late evening tonight we will be coming closer again, making a landfall around 4 am in the morning.

The weather outside is beautiful with the sun shining with a gentle breeze from the North East. However as we are going against that it feels like a strong breeze on the deck when the ships speed and the wind speed are combined into the relative wind speed on deck. The Brazil current that has been going against us is less pronounced over here as we are in deep water. As our straight course line is moving us away from the shore, we are also to the East of the shallow waters in front of the coast. (Shallow meaning about 200 feet or so) Here the water is over 7000 feet deep and that means that the current has more room to flow and is not concentrated in a shallow depth of 200 feet. Hence we only have a knot against us.

The ships bulb; designed to push away the waves before they would hit the sharp end of the bow and so reduce the ships resistance through the water.

Because of the nice weather and the very steady ride that we are having, we had the opportunity to do some testing with the optimum trim of the vessel to conserve fuel. Each ship has an optimum trim (that is the relation of the draft at the bow and the stern and the ships speed) and it is worthwhile to have it for each speed setting as it can save a significant amount of fuel. Most cruise ships use the least fuel when the trim is by the bow. E.G the draft forward is more than aft. The bulbous bow comes more under water and that reduces the resistance that the ship experiences while pushing through the waves. The question always is what is the best trim; how deep should the bow go. That varies from ship to ship and depends on a lot of factors. First all there is the average draft which is a result of the total weight in the ship. When we have loaded fuel in a port, the ship will be deeper in the water than when we are almost empty. Also when making speed, there is the squat. The sinking in of the stern, due to the grip of the propellers into the water. But apart from the stern going in, the whole ship also sinks in a little bit as well. Thus the forward and aft drafts are both affected. This results in the fact that the optimum trim over the bow is not always standard.

So today we experimented a little bit by adding ballast (that is seawater) into the forepeak tank. (The foremost tank in the ship, just behind the Bulbous bow)This brought the bow deeper in the water and changed the flow of the water around the bulbous bow. With the steady weather and current of today, we could now observe all day long if the speed of the ship increased. More speed, means covering more distance with the same fuel consumption and thus we save some. In the course of the day, we saw the speed climbing by about 0.25 of a knot. Not much on face value but over a period of time it adds up.

We will keep doing these experiments during good weather days and eventually we will have a good idea what will be the optimum trim of draft under which circumstance. For tomorrow morning on arrival, I will need the ship to be trimmed slightly over the stern, so that my stern thruster is fully submerged for maneuvering.